The Brain Exhibit

Human Brain Anatomy

The brain weighs about 3 pounds and has three main parts: the cerebrum, the cerebellum
and the brain stem. When removed from the skull, the human brain is as soft as Jello.
For preservation, brains are treated with chemicals such as formaldehyde. These were
carefully dissected and encased in plastic blocks. The brains not encased in plastic
blocks were hardened with liquid plastic in a process called plastination.

These brains have been collected from autopsies performed by the Department of Pathology
and Laboratory Medicine at the University of Tennessee Health Science Center and from
cadavers donated to the Department of Anatomy, University of Tennessee at Knoxville
and UTHSC.

Horizontal Section of a Human Brain

The dark area in the brain stem, marked by an arrow, is called substantia nigra. Many
of the cells in this area would be lost in patients with Parkinson's disease.

Comparing Animal Brains

In general, larger animals tend to have larger brains. However, larger brains do
not always equate to intelligence and thinking ability. If the ratio of body weight
to brain weight were considered, the squirrel monkey's brain is larger than a human
brain. The squirrel monkey, a small South American monkey, may be clever, but it
is not a great thinker. Intelligence and cognitive ability are functions of density,
number of neurons and surface area of the brain. The size of various areas of the
brain is also important. The neocortex, is the area of the brain which controls social
relationships, and reasoning. It makes up 16 percent of the brain in insect-eaters
and 80 percent in humans.

Brain Diseases Awareness and Prevention

The brain is surrounded by three protective coverings known as the meninges. These
are the pia mater, the arachnoid layer and the dura mater. The pia mater adheres to
the brain; the dura mater lines the inside of the skull and the arachnoid layer lies
in between the pia and dura mater. Head injuries may cause bleeding between these
layers. The use of automobile seat belts and bicycle helmets can reduce many of these
injuries. Increased blood pressure may cause hemorrhage deep inside the brain.

Meningitis: Infection of the meninges is known as meningitis. Vaccines may prevent meningitis.
Infection of the meninges by bacteria, viruses, or fungi causes meningitis resulting
in high fever, headache, and stiff neck. The specimen illustrates the thickened and
opaque meninges, characteristic of bacterial meningitis.

Subdural Hemorrhage or Hematoma: Injuries to the head often result in bleeding under the membranes covering the brain.
Bleeding under the dura mater is called subdural hemorrhage or hematoma. Wearing a
seat belt can help reduce the impact on the brain during an automobile accident. In
this specimen a subdural hematoma is marked by an arrow.

Cerebral Hemorrhage: The dark clot on the left side of this specimen is a "cerebral hemorrhage," a bleed
in the substance of the brain. Hypertension (high blood pressure) can cause this type
of hemorrhage, which the patient expresses as a stroke. Check your blood pressure
regularly and consult a physician if it is increased.

Cancer: Cancer from many organs can spread to the brain. This specimen shows spread of lung
cancer to the brain. The arrows show the cancer tissue. Smoking is one of the main
causes of lung cancer.